Lasers, as is known, are well established as effective means for performing precise operations in myriad surgical and industrial applications. Various forms of surgical lasers, for example, may be found in U.S. Pat. Nos. 3,710,798, 3,865,114, 4,122,853, 4,420,431, 4,644,948, 4,911,711, 4,950,268 and 4,994,058.
In treating topical dermatological lesions such as port wine stains, warts, tumors, and the like, on a patient's skin, a physician commonly employs a surgical laser to alleviate or, preferably, remove the lesions. In practice, the physician must move the activated laser over the area of the lesion while exercising great care not to irradiate the surrounding skin, a process that is both time consuming and painstaking. As a consequence, a typical lesion is, at present, normally treated only once or twice at high power, resulting in conditions under which the lesion frequently does not favorably respond.
Attempts to reduce the time and effort required to perform surgical laser treatment of skin lesions have been proposed. One such system involves a computer, video equipment and a laser-carrying robotic arm. In this system, video images of the lesion boundary are processed by the computer which in turn controls the movement of the robotic arm. When the computer, via the processed video images, detects a boundary of the lesion, the computer sends signals to redirect the movement of the robotic arm such that the laser maintains radiation application within the confines of the area of the lesion. Due to its complex design and construction, however, this system is costly and its usage is presently limited essentially to experimental treatments. Further, with such a system, the physician does not directly control the laser. As a consequence, should one or more of the sophisticated components of the system malfunction during the treatment, the skin surrounding the lesion may become unintentionally radiated and/or the lesion over-radiated. Hence, concentration and attention to the condition of not only the patient but also the functionality of the treatment equipment must be strictly maintained throughout the treatment process.
U.S. Pat. No. 4,122,853 teaches of a laser for use in surgical procedures designed to treat affected tissue without irradiating healthy tissue. Specifically, there is described an infrared laser photocautery device that contains an infrared transparent window in its tip which permits the tip to be brought into contact with biological tissue to be cauterized while excluding surrounding tissue from the effects of the beam. If skillfully manipulated, such a device may reduce inadvertent radiation of healthy tissue. However, as with related laser treatments, the physician must at all times exercise extreme caution not to permit the laser energy from crossing the lesion boundary.
A further problem attendant to laser surgical treatment is the potential for unintentional release of laser radiation into the operation room, such as, for example, when the laser is dropped or accidentally turned away from the target area. U.S. Pat. No. 4,950,268 describes a system for deactivating a surgical laser when laser light is aimed in a direction other than toward the surgical area. However, this system operates by way of a photosensor which is disposed adjacent to the laser housing and which is directed obliquely toward a wall or ceiling surface in the room in which the laser is being used. Should the photosensor detect stray reflected laser radiation in the operation room, the laser is deactivated by control circuitry. Although such a system may be generally effective, a serious disadvantage thereof is manifest, i.e., if the laser were to somehow become misdirected from the surgical area and some object blocked the inadvertently misguided laser radiation from reaching, in at least detectable levels, the room area at which the photosensor is directed, the laser would remain activated and continue to release the potentially damaging laser radiation into the operating room.
An advantage exists, therefore, for any laser, including, but not limited to, a surgical laser, an industrial laser, and the like, having sensing and control systems for automatically and reliably deactivating the laser when the laser radiation is directed at an area not intended to be treated by the laser and when the laser is inadvertently misdirected from a target area.